01 -
Cut the puff pastry into medium-sized triangles measuring approximately 2 inches.
02 -
Bring a pot of water to a boil, add the chicken breasts, and cook for 30 minutes or until fully cooked. Allow the chicken to cool and reserve the chicken broth. Shred the chicken using two forks.
03 -
Heat a non-stick skillet over medium-high heat, add olive oil and butter, and let them melt. Add diced onion and minced garlic, cooking for 5–7 minutes until softened.
04 -
Add chopped celery and carrots to the skillet, cooking for a few more minutes. Stir in frozen peas.
05 -
Sprinkle flour evenly over the vegetables and mix well. Gradually stir in cream and chicken broth while mixing. Cook until the sauce thickens. Season with thyme, salt, and black pepper. Remove from heat.
06 -
Preheat the oven to 180ºC. Grease a baking dish. Layer ⅓ of the puff pastry triangles on the bottom, followed by ½ of the chicken mixture. Repeat the layers and finish with a top layer of puff pastry. Brush the top with egg white.
07 -
Bake the casserole for 25 minutes or until the pastry is golden brown.
08 -
Remove from the oven. Serve immediately and enjoy.